Where Hollywood actors may be, spouting leftism (4,3)
I believe the answer is:
film set
'where hollywood actors may be' is the definition.
(I know that film actors are often found at film sets)
'spouting leftism' is the wordplay.
'spouting' is an anagram indicator.
'leftism' with letters rearranged gives 'FILM SET'.
(Other definitions for film set that I've seen before include "Picture arrangement" , "Ealing location?" .)